A new twist of rubredoxin function inM. tuberculosis

Abstract

Electron transfer mediated by metalloproteins drives many biological processes. Rubredoxins are ubiquitous iron-containing electron carriers that play important roles in bacterial adaptation to changing environmental conditions. In Mycobacterium tuberculosis, oxidative and acidic stresses as well as iron starvation induce rubredoxin expression. However, their functions during M. tuberculosis infection is unknown. In the present work, we show that rubredoxin B (RubB) supports catalytic activity of mycobacterial cytochrome P450s, CYP124, CYP125, and CYP142, which are important for bacterial viability and pathogenicity. We solved the crystal structure of RubB and characterized the interaction between RubB and CYPs using site-directed mutagenesis. Mutations that neutralized single charge on the surface of RubB did not dramatically decrease activity of studied CYPs, and isothermal calorimetry (ITC) experiments indicated that interactions are transient and not highly specific. Our findings suggest that a switch from ferredoxins to rubredoxins support CYP activity in M. tuberculosis-infected macrophages. Our electrochemical experiments suggest potential applications of RubB in biotechnology.

Mycobacterial DNA-binding protein 1 is critical for BCG survival in stressful environments and simultaneously regulates gene expression

“…RubA and RubB, code for the iron-sulphur protein ruberodoxin which rapidly transfer metabolic reducing equivalents to oxygen or reactive oxygen species. They are preferably induced during oxidative stress since they are less affected by oxidative stress and only need one iron ion, which is especially useful in macrophage environment where iron is scarce 59 . On the other hand, whiB3 proteins have been associated with a myriad of functions including sensing and responding to oxidative and nitrosative conditions.…”

Sequential Allylic Alcohol Formation by a Multifunctional Cytochrome P450 Monooxygenase with Rare Redox Partners

“…In our knowledge, these proteins which contain iron(s), but not possess inorganic sulfide, have not yet been reported as electron donors for CYPs [21] . Only recently, it was shown that viability‐ and virulence‐related CYP from Mycobacterium tuberculosis could use rubredoxin instead of ferredoxin under iron‐deficient conditions [22] . However, both CYP‐rubredoxin and ‐ferritin‐like protein systems are unprecedented in the context of specialized biosynthetic pathways.…”